Ive got a guilty astronomy secret – -Ive never seen Jupiter’s great red spot – until tonight.
Anytime Ive looked, I havent been that sure and since Jupiter rotates every 10 hrs, there is a fair chance it wont be visible.
To help with this, I downloaded Sky and Telescope magazine’s JupiterMoons app for iPAD which has a GPS animation of Jupiter revolving so you know when the GRS will be there. It also shows you the transit times of Jupiter’s 4 moons and the shadows that they cast on the planet.
Armed with the information that the GRS would be right in the middle of Jupiter at 1942 hrs and Io would be casting a shadow as it transited, I set up with the Nexstar 8SE.
I used a 31mm Hyperion eyepiece to get aligned then gradually worked down through a 10mm Delos, (x200 mag) 8mm Vixen VLW (x250 mag) and 5mm Vixen NLV (x400 mag) eyepieces. The best views were with the Delos – I could clearly see the GRS and the shadow of Io as it transited at about 1920 hrs. I just had time to do one very quick CCD run in B&W at about 1940 hrs in which you can make out the GRS as a sort of belt buckle in the middle of the lower dark belt of Jupiter and the shadow of Io – well, thats, the little dark spot to the upper right of the same belt!